I agree that double blind studies should be the standard for FDA approval of claims, and certainly for prescription status (this is actually a lower threshold than the clinical trial process they often demand which involves many such trials in a variety of settings). However, the price of such certainty (and no doubt increased safety) is that many promising and effective, natural agents will never see the marketplace due to financial, patent, and other considerations. Alpha Lipoic acid for instance is approved in Germany for the treatment of diabetic and alcoholic related neuropathies. I have listed a few of the scientific papers published upon it's merits below. Of course these do not constitute, the type of large scale, double blind experiments required for FDA approval. In the case of alpha-lipoic acid why would anyone spend the millions required to fund such trials when the agent cannot be patented (save perhaps for the NIH which might consider funding such research were it not for a limited budget under the auspices of it's Institute for Complementary and Alternative medicine).
To the extent that I use supplements at all, I try to stick with those which have significant, scientific support from reasonably non bias scources. However, I am under no illusions that such support is equivalent to the FDA clinical trial process. I have visited quackwatch on several occasions and often agree with their perspective (I once took one of their articles to my advanced physiology professor when he mentioned colloidal minerals). There are many examples of current "mainline" approaches (such as taking an aspirin after an MI) that were once consdered CAM despite significant (but not sufficient for the FDA) clinical evidence for their efficacy. There are even current dietary approaches such as caloric restriction with adequate nutrition that have over fifty years of extensive scientific support in numerous animal models (and less in humans because we live so much longer), but are still not advocated in the mainline scientific/medical community. You are correct however in pointing out that attempting to utilize such approaches entails a higher level of risk that they may be harmful or just not effective. It really comes down to caveat emptor.
ALPHA-LIPOIC ACID REFERENCES
1. Kramer K, Packer L. R-alpha-lipoic acid. In: Kramer K, Hoppe P, Packer L, eds. Nutraceuticals in Health and Disease Prevention. New York: Marcel Dekker, Inc.; 2001:129-164.
2. Packer L. alpha-Lipoic acid: a metabolic antioxidant which regulates NF-kappa B signal transduction and protects against oxidative injury. Drug Metab Rev. 1998;30(2):245-275. (PubMed)
3. Biewenga GP, Haenen GR, Bast A. The pharmacology of the antioxidant lipoic acid. Gen Pharmacol. 1997;29(3):315-331. (PubMed)
4. Bast A, Haenen GR. Lipoic acid: a multifunctional nutraceutical. In: Kramer K, Hoppe P, Packer L, eds. Nutraceuticals in Health and Disease Prevention. New York: Marcel Dekker, Inc.; 2001:113-128.
5. Packer L, Kraemer K, Rimbach G. Molecular aspects of lipoic acid in the prevention of diabetes complications. Nutrition. 2001;17(10):888-895. (PubMed)
6. Biewenga GP, Veening-Griffioen DH, Nicastia AJ, Haenen GR, Bast A. Effects of dihydrolipoic acid on peptide methionine sulfoxide reductase. Implications for antioxidant drugs. Arzneimittelforschung. 1998;48(2):144-148. (PubMed)
7. Zhang WJ, Frei B. Alpha-lipoic acid inhibits TNF-alpha-induced NF-kappaB activation and adhesion molecule expression in human aortic endothelial cells. Faseb J. 2001;15(13):2423-2432. (PubMed)
8. Mizuno M, Packer L. Effects of alpha-lipoic acid and dihydrolipoic acid on expression of proto-oncogene c-fos. Biochem Biophys Res Commun. 1994;200(2):1136-1142. (PubMed)
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11. Hagen TM, Ingersoll RT, Lykkesfeldt J, et al. (R)-alpha-lipoic acid-supplemented old rats have improved mitochondrial function, decreased oxidative damage, and increased metabolic rate. Faseb J. 1999;13(2):411-418. (PubMed)
12. Suh JH, Shigeno ET, Morrow JD, et al. Oxidative stress in the aging rat heart is reversed by dietary supplementation with (R)-(alpha)-lipoic acid. Faseb J. 2001;15(3):700-706. (PubMed)
13. Hagen TM, Liu J, Lykkesfeldt J, et al. Feeding acetyl-L-carnitine and lipoic acid to old rats significantly improves metabolic function while decreasing oxidative stress. Proc Natl Acad Sci U S A. 2002;99(4):1870-1875. (PubMed)
14. Liu J, Head E, Gharib AM, et al. Memory loss in old rats is associated with brain mitochondrial decay and RNA/DNA oxidation: partial reversal by feeding acetyl-L-carnitine and/or R-alpha -lipoic acid. Proc Natl Acad Sci U S A. 2002;99(4):2356-2361. (PubMed)
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16. Jacob S, Henriksen EJ, Schiemann AL, et al. Enhancement of glucose disposal in patients with type 2 diabetes by alpha-lipoic acid. Arzneimittelforschung. 1995;45(8):872-874. (PubMed)
17. Konrad T, Vicini P, Kusterer K, et al. alpha-Lipoic acid treatment decreases serum lactate and pyruvate concentrations and improves glucose effectiveness in lean and obese patients with type 2 diabetes. Diabetes Care. 1999;22(2):280-287. (PubMed)
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33. Heitzer T, Finckh B, Albers S, Krohn K, Kohlschutter A, Meinertz T. Beneficial effects of alpha-lipoic acid and ascorbic acid on endothelium-dependent, nitric oxide-mediated vasodilation in diabetic patients: relation to parameters of oxidative stress. Free Radic Biol Med. 2001;31(1):53-61. (PubMed)
34. Haak E, Usadel KH, Kusterer K, et al. Effects of alpha-lipoic acid on microcirculation in patients with peripheral diabetic neuropathy. Exp Clin Endocrinol Diabetes. 2000;108(3):168-174. (PubMed)
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41. Maitra I, Serbinova E, Tritschler HJ, Packer L. Stereospecific effects of R-lipoic acid on buthionine sulfoximine-induced cataract formation in newborn rats. Biochem Biophys Res Commun. 1996;221(2):422-429. (PubMed)